"This persuasion cometh not of him that calleth you." This persuasion is that of not running well, of not being faithful to the truth which has been taught and of not obeying the truth. These ones who had a perverse persuasion, no doubt, had been taught to keep the true persuasion of continuing in the grace of God (Acts 13:43). God did not teach them this perverse persuasion. God has rather ordained that people are saved through the preaching of the true gospel: 1 Cor. 1:21 For after that in the wisdom of God the world by wisdom knew not God, it pleased God by the foolishness of preaching to save them that believe.
In verse nine Paul speaks of a "whole lump." This regards the whole membership of a specific local church, the whole church (See Acts 15:22; Rom. 16:23; 1 Cor. 14:23). But it takes only a little leaven to leaven the whole lump. Sometimes it takes only one member of a local church who has a perverse persuasion to leaven the entire church, turn the whole tenor of biblical preaching to that of a perverse gospel (See 2 Cor. 11:4; Gal. 1:6). How many modern churches have been leavened by one or two members of a local church? Many churches have changed their names from Baptist to one and another name relating the changes that are apparent in the leaven that has been planted in the church. Once that leaven begins to work, many changes can take place, and what used to be a good, sound, doctrinal church is now an organization with varying, changing doctrines to please people rather than God. This is the character of leaven.
There is a man in one or more of the Galatian churches who is causing problems with the truth, changing the truth of God into a lie and has become a false teacher, no doubt. It seems from verse ten that the majority of the churches in Galatia were primarily bent toward truth; but, remember, a "little" leaven will leaven the whole lump. The one who "troubleth you" will bear his own judgment. If this person leavens the whole church, then the church will suffer; but if this person is recognized and the church deals with the problem, only the person troubling the church will be under judgment. Many churches have come under judgment due to one person's leaven. God will not endure leaven. Notice Rev. 2:5 Remember therefore from whence thou art fallen, and repent, and do the first works; or else I will come unto thee quickly, and will remove thy candlestick out of his place, except thou repent.
Churches should repent of their fallen condition and do their first works, the works that established them in the Lord Jesus Christ. God will "come unto thee quickly" and remove the church's effectiveness and authority if we do not. May God show us the truth in a plain way and give us the insight and the will to correct our problems, dismiss any false teachers, and "endure hardness as a good soldier of Jesus Christ" (2 Tim. 2:10).